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Von Karman Vortex Street

Discussion in 'Sailing Talk' started by NightSailor, Jul 30, 2009.

  1. NightSailor Captain

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    Who knows what this has to do with sailing?

    This is the basic pattern. Look for it in all the other photos.

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  2. Zeppo Guest

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    Masthead turbulence?
  3. NightSailor Captain

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    Not what I'm looking for. Not that you are wrong. How can you use this to you advantage from a safety perspective?

    I'll let other people give their guesses and get back in when I can in the next few weeks. I'll be off sailing.
  4. Tillerman Guest

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    When a sailing boat is hove to in heavy seas, it creates a wake on it windward side as it drifts downwind. This wake, which is actually a Von Karman Vortex Street, smooths down the approaching breaking waves. If the boat puts out a sea anchor it will also create its own Von Karman Vortex Street providing even more protection for the vessel.
  5. NightSailor Captain

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    Good answer. I use these pictures to explain how effective the Von Karman Vortex Street as it applies to boats hove-to.

    Now can you tell me how far upwind a hove-to boat will diminish the wave train to windward?
  6. Tillerman Guest

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    Larry Pardy has reported that the waves start to lose their power in the slick created by the Von Karman Vortex Street as much as a 1/4 to 1/2 a mile to windward while drifting downwind at 5/8 to 3/4 knot in 70 knot winds.
  7. SFBayLaser Restricted Member

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  8. Tillerman Guest

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    "Karman vortex shedding is a self-excited limit-cycle oscillation of the entire near wake reached via a supercritical Hopf bifurcation of the steady wake at the critical Reynolds number of Rc ~48."

    Well yeah. Isn't that basically what I said?

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